The present invention relates to the collection and identification of microorganisms and, while it is most suitably described in such context, it must be realized that its structure may be applied in other uses without departing from its inventive concept.
Bacterial diseases are diagnosed and treated by the isolation and identification of causative microorganisms. Conventionally, medical therapy should only be initiated after determination of the etiologic agent. This determination is based primarily on clinical information, but confirmatory laboratory data should always be sought to aid and permit appropriate management of the infective disease. Clinical tests for bacterial identification depend upon comparison of a number of physiological, morphological, and positive and/or negative biochemical reactions for the suspect etiologic agent and comparing these with the reactions of known species. To accomplish this task, it is necessary to obtain specimen cultures of the organism from such sources as sputum, blood, urine, etc., and submit of these samples to identifying procedures.
This means of identification is complex and time-consuming and concomitantly prone to possible error and mis-identification. Moreover, the time-consuming nature of the many tests which must be conducted places a burden on the cost of laboratory operation and excessive employment of skilled personnel for long periods of time.
Various methods and apparatus have been employed in an attempt to facilitate the identification of micoorganisms. These are primarily directed to expediting the cumbersome process and rendering the identification more positive. One such device is described in U.S. Pat. No. 3,784,448, which discloses a separately compartmented tube containing pre-prepared culture media for differential identication of microorganisms, particulary of the Enterobacteriaceae family. In using this device, a rigid rod-like member containing a culture of the organism is withdrawn through the tube thereby inoculating each of the chambers. This prior art device is limited by the number of tests available for use in the unit and by its cost as well as storage and stability problems.
To date, a most successful advance in this area of clinical laboratory testing involves the use of bibulous paper or other absorbent substrate impregnated with reagents which detect the presence of specific enzymes or metabolic end products characteristic of certain microorganisms. These reagents include a substrate to be acted on by a specific bacterial enzyme and a detection system which reacts with the metabolic end product to yield a readily identifiable color change. U.S. Pat. Nos. 3,122,480, 3,341,427, 3,359,180, 3,378,346, 3,597,321, 3,616,258, 3,645,853 and 3,649,461, which are incorporated in this application by reference, and modifications thereof disclose the preparation and formulation of the various substrate and detection reagents as well as their application to the identification of certain organisms.
A typical application of these techniques involves the following materials and process steps:
1. Paper strips containing suitable substrate and detection reagents are prepared for a number of specific biochemical tests, for example, Voges-Proskauer, nitrate reduction, phenylalanine deaminase, urease, indole, lysine decarboxylase, etc.
2. Test tubes corresponding to the number and order of the tests to be performed are placed in a rack.
3. Bacterial colonies cultured on or in a suitable nutrient, for example, an agar medium, are transferred to and suspended in a tube containing 0.3 ml. of saline for each test to be used. The resultant suspension should have a turbidity approximately equal to a Kirby Baver Standard.
4. Approximately 0.3 ml. of the suspension is pipetted into each of the test tubes.
5. Test strips corresponding to the specific test are added to each of the test tubes and incubated therein for approximately four hours at a temperatures of 35.degree.-37.degree. C.
6. The positive or negative indication of the test is then read from the color of the substrate zone where appropriate, as for example in the lysine decarboxylase test, or the tube is tipped so that the incubated suspension moistens the detection zone where again the color change or absence thereof gives rise to a positive or negative indication, as in the Indole Test, for example.
This test procedure has proven extremely successful, giving accuracy results as good as standard laboratory procedures in a much shorter time. To aid in the determination of the exact organism involved based upon the probabilities determined by each of the specific tests, U.S. Pat. No. 3,957,586 describes one type of an identification system providing for rapid and accurate determination of the causative agent. This system employs a number of punch-coded test data cards which, when placed in registration, give an indication as to the identification of the organism involved according to known principles of Boolean logic. Another approach is the use of a computer program dictionary, based on actual number systems, to provide probability of identification.
It is to further enhance and facilitate the foregoing test procedure that the present invention is directed. Although the rapid reagent-impregnated strip test identification procedure has greatly shortened the time involved and increased the accuracy of organism identification, it is considered that this test may be further enhanced by the utilization of a device which would obviate the need for a plurality number of test tubes as well as the commensurate time and care needed in their handling, cleaning and preparation. The invention envisions a device designed for ease of handling while still allowing rapid and accurate identification.
It is therefore an object of the present invention to provide an improved diagnostic device for the rapid and accurate identification of microorganisms. It is another object of the invention to provide a unitary disposable device for the performance of a series of biochemical tests. It is yet another object of the present invention to provide a device which facilitates rapid and easy inoculation with a test specimen and visual assessment of the test results. Yet another object of the present invention is to provide a test device containing therein substrate and/or detection reagents for the identification of microorganisms.